1. Field of the Invention
The present invention relates to an image display device and, more particularly, to a technique for making a reflective electrode surface uneven.
2. Description of the Background Art
In a reflective liquid crystal display device as an example, a reflective electrode for reflecting external light toward a liquid crystal layer is connected to a pixel TFT, with an organic insulation film therebetween. Main reasons for the use of the organic insulation film are that the low relative dielectric constant of the organic insulation film reduces unnecessary capacitances between the reflective electrode and interconnect lines and that the increased thickness of the organic insulation film can be easily achieved.
Japanese Patent No. 3564358 discloses a technique for making the surface of the organic insulation film uneven to make the surface of the reflective electrode accordingly uneven, thereby providing a display device having a high level of visibility. In the technique disclosed in Japanese Patent No. 3564358, the unevenness of the surface of the organic insulation film is achieved by a photolithography process after the formation of the organic insulation film.
In recent years, a driving circuit has been formed on a peripheral portion of a substrate on which pixels are formed, whereby the size reduction of the display device has been accomplished. In the future, it can be expected that a controller circuit or the like in addition to the driving circuit will be formed on the same substrate. However, such a technique has presented a problem in reducing the proportion of a display area on the substrate.
Japanese Patent Application Laid-Open No. 10-104663 (1998) discloses a technique for solving the problem as mentioned above. The technique disclosed in Japanese Patent Application Laid-Open No. 10-104663 increases the proportion of the display area in the area of the substrate by forming at least one logic circuit partially or entirely under the reflective electrode within the display area.
However, simply combining the technique disclosed in Japanese Patent No. 3564358 and the technique disclosed in Japanese Patent Application Laid-Open No. 10-104663 together presents a problem such that the process of making the surface of the reflective electrode uneven requires the addition of another photolithography process step after the at least one logic circuit is formed partially or entirely under the reflective electrode, thereby resulting in an increased number of manufacturing steps.